1. Field of the Invention
The present invention relates generally to polymeric compositions having at least one polyimide domain and at least one doped polyaniline domain. More specifically, the compositions of the present invention can be created by incorporating a stable, doped polyaniline dispersion into a polyamic acid (a polyimide precursor material). The mixture is processed to form a blended polymer substrate (polyimide+doped polyaniline) without having undue gelling or agglomeration of the doped polyaniline particles.
2. Discussion of the Related Art
Polyimide compositions containing electrically conductive doped polyaniline filler particles are known. U.S. Pat. No. 5,567,355, to Wessling et. al., teaches a method of forming a doped polyaniline dispersion having an average particle size of less than 500 nanometers. However, such compositions tend to have low gloss factor and/or a rough surface when used in polyimide blends.
G. Min disclosed procedures for the preparation of polyimide-polyaniline blends in Synth. Met. Vol. 102 (1999), p. 1163-1166, A Solution Blending Method. A solution of un-doped polyaniline (also called “Emeraldine base” or “EB”) is prepared in a polar organic solvent (e.g. dimethylacetamide) in which the polyamic acid (polyimide precursor) is also soluble. Then, the two solutions are mixed and the resulting mixture cast and dried. The resulting polyimide-EB blend is subsequently doped using hydrochloric acid or other protonic acid dopants. However, gelation can be problematic for this type of process, particularly when manufacturing and storing the polyaniline (EB) solutions.